Self-illuminated camera heads are ubiquitous, being used in a host of applications ranging from inspection of municipal sewage pipes to endoscopic surgical procedures. Of particular interest herein is pipe inspection, although the invention is not limited to this application. A camera head used for pipe inspection typically comprises an imaging device for converting the image to an electrical signal, a lenses for focusing the image, lighting for adequately illuminating the field of view, a housing to hold the lighting, lenses, and imaging device in a single unit, typically referred to as the head, and a support system for providing the necessary electrical interface and mechanical interconnection to support and position the camera head. Such support systems are known, and include, for example, wand devices, push cameras (e.g., See-snake, SnakeEye III, Pilit, Vi-Vax, and Verisight), and robotic arms.
Although camera heads used in such applications have been commercially available for some time, applicant has identified a number of shortcomings in these devices. For example, adjusting the focus of these devices tends to be problematic. In fact, many such devices have no means of adjusting the focus—the lens and an imaging device are preconfigured in a package such that adjustment of the field of view and the focus is prohibited.
Furthermore, those devices that do provide for adjustable focus tend to be awkward to use. For example, one prior art approach requires using a tool that is inserted in the front of the device to engage the lens, at which point, the lens may be turned one way or the other to adjust its focus. Such an approach, however, is inconvenient for a number of reasons. First, it requires a tool that is likely to lost or not available over the course of the instrument's useful life. Additionally, because the tool is inserted in the front of the camera head, the lens cannot be adjusted while the camera is in use. In other words, the need to approach the imaging head from the front to adjust the lens prevents a user from adjusting the lens in situ because the field of view and the light will necessarily be obscured by the tool and user's hand.
Another prior art approach for adjusting the lens involves a device having a front portion, which contains the lens and the lights and which is capable of being rotated such that the position of the lens changes relative to the imaging device. Although this approach allows for in situ adjustment of the lens (i.e., the user's hand is not in the way of the imaging device), it also is configured such that the lights are rotated with the lens. Such a configuration necessarily requires a relative complex electrical interface to provide power to the lights. In other words, an electrical interface, such as contact pins or slip ring, which allows for movement between components while still maintaining an electrical connection is required between the lights and their power source. Such an interface, however, is complex, and tends not to be as reliable as a static electrical connection because the parts tend to wear out over time, resulting in open/shorted circuits and diminished electrical performance.
Applicant has also identified that prior art camera heads also do not lend themselves to substituting one lens assembly for another to change the field of view. That is, the prior art devices tend to integrally package the lens assembly with the head such that interchanging the lens assembly is difficult, if not impossible, in the field. Therefore, if different fields of view are desired, the user is often forced to purchase different camera heads with different lens assemblies.
What is needed is a camera head having an adjustable lens that requires no tool, avoids the needs for complex electrical interfaces, and facilitates interchangeable lens. The present invention fulfills this need among others.